Effects of low oxygen on photosynthesis, translocation and growth in green pepper (Capsicum annuum)

Green pepper (Capsicum annuum cv. Bell Boy) plants were exposed in chambers to low (2%) oxygen and controlled carbon dioxide concentrations. Vegetative and fruiting plants showed short-term increases in net photosynthesis in low oxygen or elevated carbon dioxide (up to 900 μl CO2 l−1). Photosynthesis of young vegetative plants increased in low oxygen in the short-term but there was no long-term benefit. Low oxygen enhancement of photosynthesis declined with time and after 10 d, leaf area and root dry weight were less than in plants grown in normal air. Labelled assimilates were translocated from leaves to other regions at similar rates in low oxygen and normal air. Low oxygen reduced respiratory losses from leaves and reduced the proportion of soluble carbohydrate converted to polysaccharide in all plant parts. Thus, low-oxygen environments decrease the utilisation of assimilates which then may lead to inhibition of photosynthesis.